A viscous-elastoplastic constitutive equation incorporating phase transformation with the application to the residual stress analysis for welding process

A viscous-elastoplastic constitutive equation of a welding stainless steel material incorporating phase transformation was proposed based on the assumption that the welding material is a mixture of several phases, and each of which possesses viscous-elastoplastic property. The heat conduction equation incorporating phase transformation and the transformation kinetics equation were also presented. The numerical algorithm and the finite element procedure related to these equations were developed and applied to the investigations of the temperature change and the distribution of the residual stress in the welding slot area of a Cr21Ni6Mo9 stainless steel pipe. The investigated result of the residual stress was in good agreement with the data measured experimentally by X-ray diffraction.